Conventionally, a catheter is used to carry out a medical treatment and so forth in an organism through a blood vessel, and a guide wire is used to guide a catheter introduced in a blood vessel to a target position. Normally, the guide wire is inserted into a blood vessel through a sheath endermically introduced in the blood vessel and is pushed to advance to the target position while a turning operation or a back and forth operation is carried out on the outside of the organism. To this end portion, a method is known that, in order to facilitate a turning operation and a back and forth operation of the guide wire, a turning force applying tool (torque device) for being grasped with fingers by the operator is connected to an end portion of the guide wire on the outside of the organism (for example, refer to Japanese Patent Laid-Open No. Hei 9-173465).
Then, if the guide wire reaches the target position, then an end portion of the guide wire on the outside of the organism can be inserted into an opening of the catheter on the distal end side to push the catheter to advance to the target position along the guide wire. Then, where a turning force applying tool is connected to an end portion of the guide wire, although the guide wire is inserted into the opening of the catheter after the turning force applying tool is removed, since the opening of the catheter is very small, the insertion operation is not easy. Therefore, an introduction assisting tool (inserter) for inserting an end portion of a guide wire into an opening of a catheter is known (for example, refer to Japanese Patent Document Laid-Open No. 2009-189386). The introduction assisting tool disclosed in Japanese Patent Laid-Open No. 2009-189386 has a structure that a distal end portion of a catheter is fixed to a groove and a guide wire is inserted from a funnel-shaped introduction portion whose diameter gradually decreases from a wide introduction port so that the guide wire is guided to the small diameter opening of the catheter.